The present invention relates to a roll paper unit for holding a roll of paper, and an image formation apparatus equipped with the roll paper unit.
Ink-jet type image formation apparatuses for forming images by ink ejection on a printing medium, and electrophotography type image formation apparatuses for forming images by use of a developer on a printing medium are known as the output device of computers and workstations. Some of the image formation apparatuses are of the type which uses selectively cut paper sheets or roll paper as the printing medium. Some of them are of the type which uses roll paper only. An image formation apparatus which uses roll paper is usually equipped with a roll paper unit. The roll paper is cut in a prescribed size by a cutter provided in the roll paper unit, and the cut paper sheets are delivered to the image formation section in the apparatus to form images. This roll paper unit has several problems (inconveniences).
A first problem is explained below.
In formation of an image on the roll paper, the front end portion of the roll paper can be placed obliquely or be cut irregularly. To prevent the delivery failure or the defective image formation by the irregularity, after exchange of the paper roll or treatment of paper jamming, the front end portion of the roll paper is usually cut off and removed, and the front end of the roll paper is registered to be at the prescribed position. This operation is called precutting. After this precutting, the cut sheet of the roll paper is delivered to the image formation section to form an image on the paper sheet. Therefore, the roll paper unit has a paper discharge path for discharging the unnecessary precut paper piece, and a paper feed path for feeding the roll paper to the image formation section. The paper path is switched selectively for paper discharge or for paper feed, as necessary. The switching mechanism has complicated construction owing to the necessary parts such as a solenoid.
The image formation apparatus having the roll paper unit mounted in a demountable manner requires the operations of mounting the roll paper unit, precutting of the front end portion of the roll paper, and switching of the paper path for paper discharge or for paper feed, which are not simple. Additionally, a mechanism is necessary for removing the precut unnecessary paper piece from the paper discharge path. Thus, the structure is complicated. This is the first problem.
Next, a second problem is explained below.
FIG. 19 shows a bar-shaped spool with a roll-paper set thereon.
Generally, roll paper 72 is paper wound in a shape of a cylinder having hollow core portion 72a as shown in FIG. 19, and is set, together with bar-shaped spool 74 inserted into core portion 72a, in the roll paper unit. Therefore, the roll paper 72 is placed coaxially with bar-shaped spool 74 in the roll paper unit. Incidentally, into the each end portion of spool 74, stopper 75 is fitted respectively to set roll paper 72 and spool 74 coaxially and to prevent the movement of roll paper 72 along the length direction of spool 74.
The roll paper unit has a spool holder for holding rotatably both ends of spool 74, so that spool 74 inserted into core portion 72a of paper roll 72 is held rotatably by the spool holder to feed the rolled paper. When the paper roll has been used up or the roll paper is exchanged to a different size of roll paper, the spool is taken out of the spool holder and is inserted into a core portion of another new paper roll, and then the spool is again set in the spool holder.
In such a roll paper unit, the spool is placed in a direction perpendicular to the feed direction of the roll paper to prevent oblique movement of the roll paper. For this purpose, the spool holder is fixed in the roll paper unit perpendicularly to the paper feed direction. This spool holder should be set removably in the roll paper unit. If the spool holder is fixed firmly to the roll paper unit, the spool cannot simply be taken out of the roll paper unit or set therein. This is the second problem.
A third problem is explained below.
In formation of an image by use of paper roll, the roll paper is cut into a prescribed size of sheets before feeding to the image formation section to form an image. For this purpose, the roll paper unit has a cutter for cutting the roll paper into the desired size. At the upstream side of the cutter in the paper feed direction, a guide plate is provided for guiding the roll paper to the cutter. Above the guide plate, a movable pressing plate made of a metal is provided for pressing the rolled paper sheet against the guide member during movement of the cutter along the roll paper sheet for cutting it. By the pressing the roll paper with the pressing plate against the guide plate, the rolled paper can be cut precisely by the cutter.
Near the cutter in the roll paper unit, a sensor is provided for detecting the roll paper. After cutting the roll paper with the cutter, the front end of the roll paper is moved forward and backward in the vicinity of the sensor. In this movement, the pressing plate is detached from the guide plate to facilitate the movement of the roll paper front. The pressing plate which is set movably for this purpose, is controlled to press the roll paper sheet against the guide plate on cutting of the roll paper, and to be apart from the guide plate during the back-and-forth movement of the roll paper front around the sensor. This requires the parts and controllers for moving the pressing plate, which makes the structure complicated. This is the third problem.
A fourth problem is explained below.
The roll paper or cut paper sheet is gripped and delivered usually by plural pairs of delivery rollers through a delivery path formed from a metal plate or the like. During the delivery of the roll paper or cut sheet, paper jamming can sometimes occur. The jamming roll paper sheet or cut paper sheet should be removed. However, the treatment of the jamming paper sheet stopping in the delivery path is conducted by opening the delivery path, releasing the delivery rollers, and removing the jamming paper by hand from a narrow space, which is a troublesome operation. This is the fourth problem.
As described above, the conventional roll paper unit has several problems.
In view of the above situations, the present invention intends to provide a paper roll unit and an image formation apparatus having a relatively simple structure and is readily handleable.
A first embodiment of the roll paper unit of the present invention for solving the aforementioned first problem constitutes an image formation apparatus which has an image formation section for forming an image on roll paper, conducts precutting of a front end portion of the roll paper, and feeds the roll paper having been cut at the front end portion in a prescribed feed direction to the image formation section, the roll paper unit
(1) being incorporated demountably into the image formation apparatus, and
(2) having a switching member for switching a paper delivery path to a direction for discharging the roll paper when the unit is demounted, and switching the paper delivery path to another direction for feeding the roll paper when the unit is incorporated into the image formation apparatus.
The roll paper unit may have
(3) a constitution such that the front end portion of the roll paper to be precut is drawn out of the image formation apparatus when the roll paper unit is incorporated into the image formation apparatus.
Further, the roll paper unit may have
(4) a cutter for precutting the roll paper at the prescribed paper discharge path when the roll paper unit is incorporated into the image formation apparatus.
The switching member may have
(5) a plate-shaped guide member which switches over a roll paper guiding face to a front side or to a reverse side corresponding to the demounted state or the incorporated state of the roll paper unit.
The plate-shaped guide member may have
(6) a protrusion for guiding the roll paper on at least one of the front face and the reverse face.
A first embodiment of the image formation apparatus of the present invention is characterized by
(7) the roll paper unit described in the above items (1) to (6),
(8) the roll paper unit having a roll paper cover for covering the roll paper unit, and
(9) a slit formed between an outside cover and the roll paper cover for discharging the precut front end portion of the roll paper.
A second embodiment of the roll paper unit of the present invention for solving the aforementioned second problem has an aperture for placing the roll paper set on a bar-shaped spool in an image formation apparatus for forming an image on roll paper, the roll paper unit being characterized in that it has
(10) a roll paper cover for closing and opening the aperture, and
(11) a pair of spool holders which are independently turned by opening and closing of the roll paper cover between the spool-removal position and the roll paper feed position with the both ends of the spool held rotatably,
(12) the pair of the spool holders are kept at the removal position when the roll paper cover is opened, and are turned from the removal position to the paper feed position by pushing with the roll paper cover when the roll paper cover is closed, and
(13) the central shaft of the above turning movement is fixed to the roll paper unit, where
(14) the roll paper unit may have a fixing member which is fixed movably in a direction approximately perpendicular to the direction of the spool shaft, and fixes the closed roll paper cover to the roll paper unit.
The second embodiment of the image formation apparatus of the present invention for solving the aforementioned third problem, having a cutter for cutting the roll paper, and forming an image on the roll paper cut by the cutter, is characterized in that it has
(15) a guide plate placed near the cutter for guiding the roll paper to the cutter, and
(16) a flexible plate-shaped member for pressing the roll paper against the guide plate for guiding the roll paper, where
(17) the plate-shaped member may be formed from a resin film.
A third embodiment of the image formation apparatus for solving the aforementioned fourth problem, which forms an image selectively on roll paper or a cut paper sheet, is characterized in that it has
(18) a roll paper unit for holding a roll paper, incorporated demountably into the main body of the image formation apparatus, and
(19) the roll paper unit has a cutter of cutting the roll paper.
A forth embodiment of the image formation apparatus for solving the aforementioned fourth problem, which forms an image selectively on roll paper or on a cut paper sheet, is characterized in that it has
(20) a roll paper unit for holding a roll paper, incorporated demountably into the main body of the image formation apparatus,
(21) a cassette for storing the cut paper sheets, and
(22) a paper delivery path for delivering the cut paper sheets stored in the cassette, and being opened when the roll paper unit is demounted from the main body of the image formation apparatus.
The above image formation apparatus of the third or fourth embodiment may have
(23) registration rollers for holding the roll paper therebetween and delivering the roll paper at a predetermined timing to the image formation Section, and
(24) a reversal-preventing member for preventing reverse rotation of the registration roller; and
(25) the roll paper unit may have such a structure that the roll paper is unwound, when the roll paper unit is demounted from the main body of the roll paper unit with the roll paper is held by the registration roller.